Scielo RSShttp://www.scielo.cl/rss.php?pid=0717-345820160005&lang=en
vol. 19 num. 5 lang. enhttp://www.scielo.cl/img/en/fbpelogp.gifhttp://www.scielo.cl
Possibility of using apple pomaces in the process of propionic-acetic fermentation]]>http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582016000500001&lng=en&nrm=iso&tlng=en
Background: In 2014, apple production in EU countries amounted to 11.8 million tonnes. A constant increase in the production of these fruits will lead to the accumulation of thousands of tonnes of apple pomace (production waste). The amount of industrial apples is the highest - their proportiononthe market is estimated at 50-60%, of which over 95% is processed into juice. The proportion of pomace in the traditional pressing method accounts for 20% offruits used. Results: Analysis of the growth dynamics of wild strain Propionibacterium freudenreichii T82 in micro-cultures using different carbon sources showed that the highest bacterial growth occurs in an environment with fructose and the most intense biosynthesis of metabolites was found in medium containing only saccharose. It has been found that P. freudenreichii T82 used apple pomaces as a source of carbon. Propionic acid biosynthesis reached its maximum value in the 120th hour of cultivation (1.771 g/L). At this time, the content of the acetic acid produced reached the level of 7.049 g/L. Conclusions: Utilization of by-products is a significant challenge for manufacturing sites and the natural environment. The solution to this problem may involve the use of pomace as a medium component for microorganism cultivation, which is a source of industrially useful metabolites. This study examined the possibility of using apple pomace as a carbon source in the process of propionic-acetic fermentation via wild strain Propionibacterium freudenreichii T82 bacteria.Buffering action of acetate on hydrogen production by Ethanoligenens harbinense B49]]>http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582016000500002&lng=en&nrm=iso&tlng=en
The buffering effect of acetate on hydrogen production during glucose fermentation by Ethanoligenens harbinense B49 was investigated compared to phosphate, a widely used fermentative hydrogen production buffer. Specific concentrations of sodium acetate or phosphate were added to batch cultures, and the effects on hydrogen production were comparatively analyzed using a modified Gompertz model. Adding 50 mM acetate or phosphate suppressed the hydrogen production peak and slightly extended the lag phase. However, the overall hydrogen yields were 113.5 and 108.5 mmol/L, respectively, and the final pH was effectively controlled. Acetate buffered against hydrogen production more effectively than did phosphate, promoting cell growth and preventing decreased pH. At buffer concentrations 100-250 mM, the maximum hydrogen production was barely suppressed, and the lag phase extended past 7 h. Therefore, although acetate inhibits hydrogen production, using acetate as a buffer (like phosphate) effectively prevented pH drops and increased substrate consumption, enhancing hydrogen production.Stenotrophomonas maltophilia isolated from gasoline-contaminated soil is capable of degrading methyl tert-butyl ether]]>http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582016000500003&lng=en&nrm=iso&tlng=en
Background: Methyl tert-butyl ether (MTBE) is a pollutant that causes deleterious effects on human and environmental health. Certain microbial cultures have shown the ability to degrade MTBE, suggesting that a novel bacterial species capable of degrading MTBE could be recovered. The goal of this study was to isolate, identify and characterize the members of a bacterial consortium capable of degrading MTBE. Results: The IPN-120526 bacterial consortium was obtained through batch enrichment using MTBE as the sole carbon and energy source. The cultivable fraction of the consortium was identified; of the isolates, only Stenotrophomonas maltophilia IPN-TD and Sphingopyxis sp. IPN-TE were capable of degrading MTBE. To the best of our knowledge, this report is the first demonstrating that S. maltophilia and Sphingopyxis sp. are capable of degrading MTBE. The degradation kinetics of MTBE demonstrated that S. maltophilia IPN-TD had a significantly higher overall MTBE degradation efficiency and rate (48.39 ± 3.18% and 1.56 ± 0.12 mg L-1 h-1, respectively) than the IPN-120526 consortium (38.59 ± 2.17% and 1.25 ± 0.087 mg L-1 respectively). The kinetics of MTBE removal by both cultures fit first-order and pseudo-first-order reaction models. Conclusions: These findings suggest that S. maltophilia IPN-TD in axenic culture has considerable potential for the detoxification of MTBE-contaminated water.Isolation of high-quality RNA from Platycladus orientalis and other Cupressaceae plants]]>http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582016000500004&lng=en&nrm=iso&tlng=en
Platycladus orientalis has a lifespan of several thousand years in China, making it a good plant in which to study aging at the molecular level, but this requires sufficient quantities of high-quality P. orientalis RNA. However, no appropriate methods have been reported for total RNA isolation from P. orientalis leaves. The TRIzol method did not extract RNA, while cetyltrimethylammonium bromide, sodium dodecyl sulfate-phenol, and plant RNAout kit (Tianz, Inc., China) protocols resulted in low yields of poor quality RNA. Isolating total RNA using the Spectrum Plant Total RNA Kit (Sigma-Aldrich, St. Louis, MO, USA) resulted in a high-quality product but a low yield. However, the two-step removal of polyphenols and polysaccharides in the improved plant RNAout kit protocol resulted in the isolation of RNA with a 28S:18S rRNA ratio of band intensities that was ~2:1, the A260/A280 absorbance ratio was 2.03, and the total RNA yield from P. orientalis leaves was high. This protocol was tested on different P. orientalis tissues of different ages and on leaves of five other Cupressaceae plants. The total RNAs were successfully used in complementary DNA synthesis for transcriptome sequencing and would be suitable to use in additional experiments. The results of this study will benefit future studies in Cupressaceae plants.Comparative proteome analysis of Brettanomyces bruxellensisunder hydroxycinnamic acid growth]]>http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582016000500005&lng=en&nrm=iso&tlng=en
Background: Brettanomyces bruxellensis is an important spoilage yeast in the winemaking process. The capacity of this yeast to generate an undesired off-flavor constitutes a significant loss in the Chilean wine industry. Results: The proteomic profile of B. bruxellensis in the presence of p-coumaric acid was determined by 2D gel electrophoresis, gel image analysis and differential spot selection. A set of 41 proteins showed a differential accumulation of ±2 and a p-value <0.0001. The homology sequence analysis was performed using the databases available. Differential proteins belonged to the categories of 'energy production and conversion' and 'amino acid transport and metabolism'. Conclusions: The proteomic profile of B. bruxellensis cultivated in the presence of p-coumaric acid in synthetic wine, agrees with the hypothesis of metabolic flux regulation, allowing a better conditioning to an adverse environment. This study involved the translational level of B. bruxellensis in the production of ethylphenols and corroborated that this yeast presented an advantage in these stress conditions. Thus, this work will allow an understanding of the regulation and processes involved in the production of ethyl-derivate compounds by B. bruxellensis. Furthermore, it allows the development of newer and better techniques for spoilage yeast control.Xylanase and β-xylosidase from Penicillium janczewskii: Purification, characterization and hydrolysis of substrates]]>http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582016000500006&lng=en&nrm=iso&tlng=en
Background: Xylanases and β-D-xylosidases are the most important enzymes responsible for the degradation of xylan, the second main constituent of plant cell walls. Results: In this study, the main extracellular xylanase (XYL I) and p-xylosidase (BXYL I) from the fungus Penicillium janczewskii were purified, characterized and applied for the hydrolysis of different substrates. Their molecular weights under denaturing and non-denaturing conditions were, respectively, 30.4 and 23.6 kDa for XYL I, and 100 and 200 kDa for BXYL I, indicating that the latter is homodimeric. XYL I is highly glycosylated (78%) with optimal activity in pH 6.0 at 65°C, while BXYL I presented lower sugar content (10.5%) and optimal activity in pH 5.0 at 75°C. The half-lives of XYL I at 55, 60 and 65°C were 125,16 and 6 min, respectively. At 60°C, BXYL I retained almost 100% of the activity after 6 h. NH4+,Na+, DTT and β-mercaptoethanol stimulated XYL I, while activation of BXYL I was not observed. Interestingly, XYL I was only partially inhibited by Hg2+, while BXYL I was completely inhibited. Xylobiose, xylotriose and larger xylooligosaccharides were the main products from xylan hydrolysis by XYL I. BXYL I hydrolyzed xylobiose and larger xylooligosaccharides with no activity against xylans. Conclusion: The enzymes act synergistically in the degradation of xylans, and present industrial characteristics especially in relation to optimal activity at high temperatures, prolonged stability of BXYL I at 60°C, and stability of XYL I in wide pH range.Assessment of microalgae and nitrifiers activity in a consortium in a continuous operation and the effect of oxygen depletion]]>http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582016000500007&lng=en&nrm=iso&tlng=en
Background: Industrial wastewaters with a high content of nitrogen are a relevant environmental problem. Currently, treatments to remove nitrogen are not efficient, so is necessary to develop alternative methods. The objective of this study is to investigate a consortium of microalgae - nitrifying, that due to the symbiosis between them could be an interesting alternative. Results: In this study, it was possible to obtain a consortium of nitrifying bacteria (NB) and microalgae (MA) capable of operating with low requirements of dissolved oxygen, using aerobic sludge from wastewater treatment plants. During the operation, this consortium presents removal percentages above 98% of ammonia, even at concentrations of DO of 0.5 mg O2 L-1. It is estimated that the removal was caused both by the action of nitrifying bacteria and microalgae. It was determined that approximately 60% of the ammonia feed was oxidized to nitrate by nitrifying bacteria, while the algae assimilated 40% of the nitrogen feed at steady state. A methodology for measuring the specific activities of nitrifying bacteria and microalgae by comparing the rates in the variation inorganic nitrogen compounds was established with satisfactory results. An average specific activity of 0.05 and 0.02 g NH4 + gVSS-1 d-1 for nitrifying bacteria and microalgae was determined, respectively. Conclusions: The consortium it can be obtained in a single continuous operation, and has a high capacity for nitrogen removal with low oxygen content. The consortium could prove to be a more economical method compared to traditional.Natural carriers in bioremediation: A review]]>http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582016000500008&lng=en&nrm=iso&tlng=en
Bioremediation of contaminated groundwater or soil is currently the cheapest and the least harmful method of removing xenobiotics from the environment. Immobilization of microorganisms capable of degrading specific contaminants significantly promotes bioremediation processes, reduces their costs, and also allows for the multiple use of biocatalysts. Among the developed methods of immobilization, adsorption on the surface is the most common method in bioremediation, due to the simplicity of the procedure and its non-toxicity. The choice of carrier is an essential element for successful bioremediation. It is also important to consider the type of process ( n s tu or ex s tu), type of pollution, and properties of immobilized microorganisms. For these reasons, the article summarizes recent scientific reports about the use of natural carriers in bioremediation, including efficiency, the impact of the carrier on microorganisms and contamination, and the nature of the conducted research.Consolidated briefing of biochemical ethanol production from lignocellulosic biomass]]>http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582016000500009&lng=en&nrm=iso&tlng=en
Bioethanol production is one pathway for crude oil reduction and environmental compliance. Bioethanol can be used as fuel with significant characteristics like high octane number, low cetane number and high heat of vaporization. Its main drawbacks are the corrosiveness, low flame luminosity, lower vapor pressure, miscibility with water, and toxicity to ecosystems. One crucial problem with bioethanol fuel is the availability of raw materials. The supply of feedstocks for bioethanol production can vary season to season and depends on geographic locations. Lignocellulosic biomass, such as forest-based woody materials, agricultural residues and municipal waste, is prominent feedstock for bioethanol cause of its high availability and low cost, even though the commercial production has still not been established. In addition, the supply and the attentive use of microbes render the bioethanol production process highly peculiar. Many conversion technologies and techniques for biomass-based ethanol production are under development and expected to be demonstrated. In this work a technological analysis of the biochemical method that can be used to produce bioethanol is carried out and a review of current trends and issues is conducted.Uniparental genetic systems: a male and a female perspective in the domestic cattle origin and evolution]]>http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582016000500010&lng=en&nrm=iso&tlng=en
Over the last 20 years, the two uniparentally inherited marker systems, namely mitochondrial DNA and Y chromosome have been widely employed to solve questions about origin and prehistorical range expansions, demographic processes, both in humans and domestic animals. The mtDNA and the Y chromosome, with their unique patterns of inheritance, continue to be extremely important source of information. These markers played significant roles in farm animals in the evaluation of the genetic variation within- and among-breed strains and lines and have widely applied in the fields of linkage mapping, paternity tests, prediction of breeding values in genome-assisted selection, analysis of genetic diversity within breeds detection of population admixture, assessment of inbreeding and relationships between breeds, and assignment of individuals to their breed of origin. This approach offers a unique opportunity to save genetic resources and achieving improved productivity. In the past years, significant progress was achieved in reconstructing detailed cattle phylogenies; many studies indicated multiple parental sources and several levels of phylogeographic structuring. More detailed researches are still in progress in order to provide a more comprehensive picture of such extant variability. This paper is focused on reviewing the use of the two uniparental markers as valuable tool for the characterization of cattle genetic diversity. Furthermore, their implications in animal breeding, management and genetic resources conservation are also reported.